Students who have academic difficulties are a sign that something is wrong. These errors can be in the form of conceptual misunderstandings, errors in forgetting the solution procedure, or careless errors. Therefore, the purpose of this study was to determine the cognitive barriers that elementary school students must overcome to understand the concept of speed and discharge. The methodology used in this study was qualitative. A literature search revealed that poor cognitive development of students, who are often at the concrete operational stage, is the main cause of these obstacles. Additional obstacles noted include proportionality challenges, limited abstraction and imagery capacity, and learning strategies that do not help the process of understanding the topic effectively.